Lecture 8 - exercise limitation Flashcards
Why is cardiopulmonary exercise testing (CPET) performed (3)?
Level of exercise intolerance
Identification of the mechanisms limiting exercise
Evaluation of disease progression and response to interventions i.e. change before and after Rx
What are the 2 locus of symptom limitation?
Dyspnea :
imbalance between the central respiratory efferent drive and the response of the respiratory muscular pump diseases
Leg discomfort:
muscle fatigue that occurs when muscle force output decreases for a given stimulus.
Causes of reduced peak VO2 in lung diseases? (3)
↓ Cardiac output
↑ in vascular pulmonary resistances
cardiac involvement
↓ Arterial O2 content
hypoventilation
↓ DLco
V/Q mismatch
↓ Oxygen utilization in tissues
sedentarism / physical inactivity
poor nutritional state
corticosteroid therapy
VEmax/MVV normal ratio?
VEmax/MVV ratio normally ≤0.80.
VEmax/MVV > 0.80 means what?
VEmax/MVV > 0.80 = possible pulmonary limitation to exercise
↓ventilatory capacity (↓ MVV)
in both obstructive and restrictive lung diseases
(MVV estimated from FEV1 x 40)
Combination of reduced MVV and increased VE (↑ VD/VT)
T/F
Expiratory flow limitation and increased EELV (static hyperinflation) with age and COPD
F
Expiratory flow limitation and increased EELV (dynamic hyperinflation) with age and COPD
T/F
Capacity for producing expiratory flow declines at lower lung volumes (decreased inspiratory muscle length).
F
Capacity for producing inspiratory flow declines at higher lung volumes (decreased inspiratory muscle length).
T/F
FRC flows come closest to the maximal available flows at the higher lung volumes.
F
FRC come closest to the maximal available flows at the higher lung volumes.
what is impaired for pulmonary gas exchange abnormlities (4)?
COPD, ILD & pulmonary vascular disease
Impaired gas exchange efficiency
↓regional V/Q and ↓ DLco
Peak exercise P(A–a)O2 30+ mm Hg
↓ SaO2 (SaO2< 88% and PaO2<55 mm Hg clinically significant)
concerning exercise with COPD patients
In COPD:
↑dyspnea intensity
breathing pattern rapid and shallow
VT larger proportion of IC at any given ventilation mechanical constraints on VT due to dynamic hyperinflation
↑ tidal inspiratory pressure swings /maximal force-generating capacity (Pes/PImax)
↓VT response /predicted VC -> ↑effort-displacement ratio .
Exercise and patient with ILD
↑ dyspnea/ VO2 sloes
↓ compliance and ↑ work of breathing -> rapid and shallow breathing pattern and ↑slope of tidal Pes/Pimax and VO2
Smaller operational lung volumes – no change in EELV with exercise and increased VT accomplished by ↑ dynamic EILV
